Epidermal growth factor (EGF) is recognized as a particularly useful treatment additive in wound treatment systems because of its role in promoting growth of epidermal skin tissue. Naturally occurring mature EGF is a 53 amino acid long polypeptide produced in vivo as the processed product of a very large (1200 amino acids long) precursor protein.
Early wound-healing systems introduced purified mature EGF as a treatment additive directly into wounds. However, the cost of treatment with mature EGF is high since the polypeptide has a short half-life in wounds. In addition, it is difficult to purify, store and administer large quantities of natural mature EGF for use in a wound treatment system as a result of its lability.
More recently, in vitro cultured skin cells such as keratinocytes and fibroblasts, some of which had been genetically modified, have been introduced into the wound-bathing fluid during treatment. These introduced cells repopulated wounded skin sites and secreted growth factors and other nutritive substances that enhance wound healing.
The concept of protecting a wound from the environment and using fluid to protect a wound is known. For example, a comprehensive treatment system for enhancing the healing of wounds, burns, skin diseases and the like is described in U.S. Pat. No. 5,152,757. The treatment system therein described includes a chamber that surrounds the wound and portals for introduction of treatment fluids and for extraction of wound fluid for monitoring and analysis. A user of the treatment system has control of various treatment variables including temperature, osmotic pressure, pH, ionic concentrations and oxygen content. Also, a user can select particular treatment additives, as indicated.
An alternate approach is desired that facilitates improved wound healing, yet eliminates the need for in vitro cell culture or for purification of EGF. What is desired is a method for delivering stable, appropriately processed EGF to epidermal cells without the difficulties that have accompanied prior efforts.